Correct fuse/cables for lighting

[ban-all-sheds]

Do take note of the details in that document of where concealed cables are allowed to run.

You mention corners, and cables above door frames - sounds like they could well be running where you're not supposed to have them buried.

 

[Ambergreen45]

Do take note of the details in that document of where concealed cables are allowed to run.

You mention corners, and cables above door frames - sounds like they could well be running where you're not supposed to have them buried.

I have read the documents a few times. All my walls are in bricks and over 100mm thick though. I also have concrete floors and ceilings. I am trying to avoid having pvc trunking showing on my walls, therefore have removed some plaster to be able to accomodate suitable conduits before realising these would be too thick because the plaster itself is only 15mm thick.

I have added two pics (sorry about the mess). On the first one the cable would be as close to the ceiling as possible to allow for a new light switch across the door. The second one would lead to an FCU for an outside light. Therefore I have been thinking to bury those cables in plaster the best way I can referring to the diagrams and wording in the documents, unless I missed something?

I have an RCCB on my CU, but it only seems to protect and isolate the plugs (wall sockets). The fuse on the CU for the ceiling lights is isolated but does not seem to be protected by the RCCB. Is this normal?

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[ban-all-sheds]

View media item 63231 View media item 63232

Both OK - in the 1st one the original route you planned around the door is what I feared - that would have been too low. And you do seem to have removed a little bit too much plaster for the 2nd one

I have an RCCB on my CU, but it only seems to protect and isolate the plugs (wall sockets). The fuse on the CU for the ceiling lights is isolated but does not seem to be protected by the RCCB. Is this normal?

It was for many years.

Now all buried cables are supposed to be RCD protected. There's no requirement to change anything just because existing ones aren't, but all new work should comply with that, so as you are adding new buried cables you should get that circuit on an RCD.

 

[Ambergreen45]

Now all buried cables are supposed to be RCD protected. There's no requirement to change anything just because existing ones aren't, but all new work should comply with that, so as you are adding new buried cables you should get that circuit on an RCD.

Once I've done the cables, I'll get an electrician to fit an additional RCD on my CU (I won't be doing that). So that I know, could he/(she) add a second RCD or will I need to have a whole new CU?

Out of interest the RCD on the CU for the plugs tripped a couple of times a few years ago (caused by a slow leaking pipe (now repaired) on the socket behind the washing machine). So I know the RCD works. However, when if I press the 'Test' button I hear a buzzing sound a bit like a door bell, instead of the fuse switching to the off position. Have you come across something like this before? Not sure whether to mention that as well.

Thanks for your help!

 

[ban-all-sheds]

Once I've done the cables, I'll get an electrician to fit an additional RCD on my CU

Wrong order of doing things.

So that I know, could he/(she) add a second RCD or will I need to have a whole new CU?

Probably the latter for a 2nd RCD, but replacing the MCB with an RCBO might be possible - depends if they make one to fit your CU.

However....

So I know the RCD works.

No - you know it was working a few years ago.

However, when if I press the 'Test' button I hear a buzzing sound a bit like a door bell, instead of the fuse switching to the off position.

And now it seems to be not working, which is not a good thing at all. I strongly advise getting an electrician in right away.